Jeff,
That is a bit of an odd pairing because you have a mix of 8-inch and 6.5-inch HLCDs. The 8-inch speaker will handle more power but will also play louder with the same amount of power. So the Pro485 will certainly dominate. A 3-Some with a single Pro485 and a pair of Pro80s is a more suitable combination.
So with what you have, a good place to begin is the generally accepted thermal rating which is 200 watts per each 8-inch and 150 watts per each 6.5-inch, although if you crossover the Pro60 a little higher than the Pro485, the Pro60 can better hang in there power handling wise.
Given that all three speakers are 4-ohms, you are looking for 150 to 200 watts for the left + 300 to 400 watts for the middle + 150 to 200 watts for the right, all into a 4-ohm load. So bridging a 4-channel amplifier into a 3-channel mode will get you close. For example, a Wetsounds Syn4 would give you 400 watts to the Pro485 (or 200 watts to each 8-inch driver) and 125 watts to each 6.5-inch driver. That's heavy on the Pro485, but very acceptable, and light on the Pro60s, especially given the fact that the 60s are not as efficient. A Wetsounds Syn6 bridged into three channels gives you excess on all channels which you can gain accordingly.
There's a power window and a start. You might find either of these amplifiers used.

Jeff,
The xdi series doesn't have a large enough 4-channel amplifier to fit your tower application. However, the KS series of Arc Audio does have a couple of amplifiers that roughly fit the above mentioned Wetsounds amplifier parameters.
Another single chassis option is the JL Audio HD600/4. This is strictly regulated so it will deliver, at minimum, it's full rated power even with a low 11 volt supply. That makes it about 30% more robust. Plus, the HD600/4 delivers the same power whether the output load is 2 or 4-ohm stereo or 4-ohm bridged. This is really two 2-channel amplifiers in a single chassis containing dual (front/rear) power supplies.